Winged migration

Global warming may be causing birds to move farther and farther north, according to an Audubon Society study released last week. More than 60 percent of 305 bird species in North America are wintering at least 35 miles farther north than they did 40 years ago. Then there are species like the purple finch (pictured) and wild turkey, which are spending their winters more than 400 miles north of their former habitat. The marbled murrelet, ring-billed gull, red-breasted merganser and spruce grouse travel more than 300 miles farther north.

Some birds not following the trend are grassland species, such as the burrowing owl and the eastern and western meadowlark. Those less adaptable birds are going to the same spots, only to find their habitat threatened by climate change, agriculture, urban and suburban sprawl and reversion to forest.

The study, which was based on data compiled through Audubon’s annual Christmas Bird Count, covers 40 years, during which time the average January temperature in the United States increased by about 5 degrees Fahrenheit.

Greg Butcher, lead scientist on the study and director of bird conservation at the Audubon Society, told the Associated Press, “It is not what each of these individual birds did. It is the wide diversity of birds that suggests it has something to do with temperature rather than ecology.”

Download the full report at www.audubon.org/bird/bacc/Species.html